Use of minimally invasive procedures, such as catheter ablation, to treat a variety of heart conditions, such as supraventricular and ventricular arrhythmias, is becoming increasingly prevalent. Often, these procedures involve the mapping of electrical activity in the heart at various locations on the endocardial or epicardial surface, referred to as cardiac mapping, to identify the mechanism of the arrhythmia followed by a targeted ablation of the site. To perform the cardiac mapping, a catheter with one or more electrodes can be inserted into the patient's heart.
Cardiac mapping techniques include contact mapping, near contact mapping, and non-contact mapping. In contact mapping, one or more catheters are advanced into the heart and physiological signals resulting from the electrical activity of the heart are acquired with one or more electrodes located at the catheter distal tip after determining that the tip is in stable and steady contact with the endocardial surface of a heart chamber. The location and electrical activity can be measured on a point-by-point basis at, for example, about 50 to 200 points on the internal surface of the heart to construct an electro-anatomical depiction of the heart. In near-contact mapping, a movable catheter having multiple spatially distributed electrodes is placed in a heart chamber of interest and moved to one or more locations within the chamber of interest, where the electrodes are on or near, such as within millimeters of, the endocardial surface of the heart chamber. Measurements are taken automatically at each of the locations of the catheter, without determining whether the electrodes are in contact with the surface of the heart. These measurements are analyzed to detect the endocardial surface of the heart chamber in the vicinity of the catheter. The location of the catheter, e.g., a location provided by a tracking system, and the measurements from the electrodes are used to reconstruct the chamber anatomy, where, for example, 20,000 measurements may be made to construct an electro-anatomical depiction of the heart. As the tracked catheter is moved inside the chamber, a partial or complete representation of the chamber anatomy can be constructed. In non-contact mapping, a multiple electrode catheter is placed in the heart chamber of interest and the catheter is deployed to assume a three dimensional shape. Using the signals detected by the non-contact electrodes and information on chamber anatomy and relative electrode location, the system calculates and provides physiological information regarding the endocardial surface of the heart chamber. In either cardiac mapping technique, the generated map may then serve as the basis for deciding on a therapeutic course of action, such as tissue ablation, to alter the propagation of the heart's electrical activity and to restore normal heart rhythm.
During cardiac mapping of a patient's heart, the mapping process determines whether a cardiac beat matches a target beat morphology. If the cardiac beat matches the target beat morphology, the signals obtained in conjunction with the cardiac beat can be mapped into a map dataset for the target beat morphology. If the cardiac beat does not match the target beat morphology, the signals obtained in conjunction with the cardiac beat may be discarded. Often, electrocardiogram (ECG) signals are used to detect the similarity between the cardiac beat and the target beat morphology. However, the industry is continuously developing new and improved systems and methods for cardiac mapping.